1. Field of the Invention
The present invention relates in general to passenger restraint devices of wheeled motor vehicles and more particularly to the passenger restraint devices of a type that includes at least a seat belt and a controller that is configured to control a set position of the seat belt in such a manner that a seat occupant (viz., belt wearing seat occupant) can be safely restrained by the seat belt upon a vehicle collision.
2. Description of the Related Art
Japanese Laid-open Patent Applications (Tokkaihei) 6-286581 and (Tokkai) 2003-175797 show passenger restraint devices of the above-mentioned type. The devices each comprise a seat belt for restraining a seat occupant, first and second pre-tensioners for applying a certain tension to the seat belt and a controller for controlling the first and second pre-tensioners in accordance with prediction and detection of a vehicle collision. The first pre-tensioner is of a reversible (or repeatable) type and the second pre-tensioner is of a non-reversible (or non-repeatable) type. That is, upon predicting a vehicle collision, the controller actuates the first pre-tensioner and upon detecting the vehicle collision, the controller actuates the second pre-tensioner, so that a belt wearing seat occupant is timely and optimally restrained by the seat belt upon the vehicle collision.